A spark plug is known from DE 101 33 229 A1. Usually, a precious metal component situated on the ground electrode is embedded in the material of the ground electrode in order to achieve a good dissipation of heat from the precious metal component. In this case, all of the side surfaces of the precious metal component, which are oriented in the longitudinal direction of the spark plug and transversely relative to the ignition surface of the precious metal component, are at least partially covered by the material of the ground electrode. The width of the ground electrode is therefore greater than the width of the precious metal component. In addition, the precious metal component does not extend all the way to the end surface of the ground electrode, but is instead slightly recessed from the end surface of the ground electrode. As a result, the precious metal component can be welded to the ground electrode along its entire circumference encompassing the ignition surface. In an exemplary embodiment from DE 101 33 229 A1, a block-shaped precious metal component is disclosed, which is situated flush with the end surface of the ground electrode. The precious metal component is nevertheless still embedded in the material of the ground electrode. It is at least partially covered by the material of the ground electrode on its two side surfaces, i.e., on a total of four out of its six surfaces.
The development of such spark plugs has already been pushed to its limits on the whole. The spark plugs have a service life that is quite long and have an operational reliability that is quite high. Development is only progressing in small steps, since it is difficult to achieve further improvements.
In the known embodiments of the ground electrode, it has been observed that cracks and chips can occur in the precious metal component, which result in ignition problems and a failure to achieve the desired service life. In such cases, the spark plug must be replaced before the next regularly scheduled maintenance of the gasoline engine, i.e., an unplanned disruption in operation.